#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int f(int n)
{
    if (n <= 2)
        return 1;
    else
        return f(n - 1) + f(n - 2);
}
int main()
{
    int n = 0;
    int a = 0;
    scanf("%d", &n);
    printf("%d\n", f(n));
    return 0;
}




#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int f(int n)
{   
    int a = 1;
    int b = 1;
    int c = 1;
    while (n > 2)
    {
        c = a + b;
        a = b;
        b = c;
        n--;
    }
    return c;
}
int main()
{
    int n = 0;
    int a = 0;
    scanf("%d", &n);
    printf("%d\n", f(n));
    return 0;
}

